For food processing/producing and feed processing/producing companies as well as for other types of companies it is important that foreign bodies are not present in and/or on the products produced. However, it may be time consuming or impossible for humans to identify and remove all foreign bodies from products as the foreign bodies may be too small to be identified by humans or foreign bodies may be present within the products such as within minced or mixed products. Examples of foreign bodies in food and feed products are bone parts, plastic, metal, cardboard/paper, stones, and ‘wrong species’ such as separating different species from each other such as separating blue or common mussel (e.g. Mytilus edulis) from cockles (e.g. Cerastoderma edule). Foreign bodies in products reduce the quality and thus the value of the products. Foreign bodies in products may thus have economic consequences for a company.
Product value can also be determined based on an agreement between a producer and a customer in respect of the quality of the produced product. If the agreement determines e.g. a certain weight or number of an ingredient in a product, the quality and thus the value is reduced if the weight or number of this ingredient is too low. In this situation the producer may obtain a lower price than if the agreement was fulfilled. On the other hand the producer may have a ‘give-away situation’ if the weight or number of an ingredient is too high as this need not result in a higher price.
Systems for performing quality control of food by the use of reflected or transmitted light in the form of visible light and near-infra red light are described e.g. in WO 08/102143 (‘Quality control of meat products using optical imaging’) which describes an arrangement having first and second light sources and an imaging device. The light sources have different wavelengths. The first light source is positioned such that the imaging device is able to take images of an object under test that is backlit by said first source of light: the second light source is positioned such that the imaging device is able to take images of the object based on light reflected from the surface of said object. In use, the imaging device simultaneously generates a first image resulting from light provided by said first light source and a second image resulting from light provided by said second light source.
US2015/0342202 (Device and method for non-contact identifying of red tissue structures and assembly for removing a strip of red tissue structures) describes an apparatus and a corresponding method for non-contact identifying of red tissue structures in products of slaughtered animal bodies, comprising a conveying device for continuous conveyance of the products in a conveying direction, a light source configured to generate a flat light field which is designed and adapted to form a light line running transversely to the conveying direction of the product from the flat light field, a detecting device for identifying the red tissue structures, which comprises at least one optical sensor means for recording the portions of light reflected by the product, wherein the light source is configured as an infrared light source and the light source is arranged such that the plane of the flat light field relative to the conveying direction is tilted by a light field angle of less than 90°.
Control of products to obtain the requested quality is of utmost importance and as requirements to food quality increases fast and reliable systems and methods for performing quality control are required. The invention described herein makes it possible to perform quality control of products especially of food and feed products and especially in respect of detecting foreign bodies and for determining number of ingredients that vary in form or structure from the remaining product.